EBACE: Beechcraft 350ER King Air is a multi-mission masterpiece

The Beechcraft King Air was introduced in 1964, and has proved to be one of the world’s most popular turboprop twins. While the folks in Wichita have been steadily working away, delivering more than 7,000 King Airs of ­various flavours since then, the corporate backdrop has been anything but stable. Multiple ownership changes and a bankruptcy filing during the course of the King Air’s production life have played out, with Beechcraft recently becoming part of Textron Aviation (TA). A visit to TA’s website reveals a new corporate tagline, “Gaining Altitude. Together.” The “together” is the combination of Beechcraft, Cessna and Hawker under a single corporate umbrella. Clyde Cessna and Walter Beech had last worked together in 1927 at Travel Air Manufacturing Company. Separately both left to found their own aircraft companies, and after 87 years apart these two storied marques are back together.

Development of the King Air 350 model, a follow on to the 300, began in 1988. Sporting winglets and a nearly 1m fuselage extension, the 350 reached the marketplace in 1990.

At the 1995 Paris air show the 350ER was announced. The ER incorporated additional fuel tanks and beefed up landing gear to handle its increased gross weight.

The 350ER gained US FAA certification in November of 1997. In 2010 I had the opportunity to fly the 350i, a 350 with an improved passenger cabin and a Pro Line 21 avionics suite. While certificated two years after the more utilitarian 350ER, it was my first exposure to the venerable King Air model line.

With due respect to the Pilatus PC-12, the King Air is the Swiss Army knife of ­turboprops and the 350ER may well be the sharpest blade on the market today.

A large cabin, simple durable systems, good field performance from unpaved runways and cruise speeds in excess of 300kts make the 350 an ideal platform for a multi-mission aircraft. Some of the roles touted by Beechcraft for the 350ER are: utility transport, air ambulance, flight inspection, aerial survey and ISR (Intelligence/Surveillance/Reconnaissance). A flight out of Mineta San Jose International Airport (KSJC) gave this reporter an opportunity to see just how sharp the 350ER’s blades are.

The turboprop's range is significantly greater than its corporate configured stablemate, the 350i

Tanked Up

The “ER” in 350ER stands for extended range. While one could argue a more accurate suffix would be MM (Multi-Mission), the preview aircraft’s N256NM registration number lent credence to the ER designation. The 350i I had flown earlier came equipped with baggage lockers aft of the engines.

The ER featured prominent fuel tanks in place of the baggage compartments. Each aft nacelle-mounted tank held 791lb/359kg (118 US gallons at 6.7lb per gallon) of Jet-A. This additional tankage gives the ER a maximum fuel load of 2,360kg. With full tanks at MTOW the ER’s VFR range (45min reserve at altitude) is 2,560nm (4,740km). Most 350ERs are delivered from the factory with a “slick” cabin that is then modified to suit the customer.

The slick cabin is about as utilitarian it can get; the only standard seat is an aft mounted forward facing toilet. The preview aircraft cabin was in a hybrid configuration: one air ambulance sled (patient litter), a system ­operator’s console and several seats. A full-up ambulance configuration can accommodate three sleds. Our preview aircraft had the standard 1.31m x 0.68m (H x W) passenger door on its aft left side.

With the aid of a rail system ambulance sleds can be loaded and unloaded through the standard passenger door. Like previous models, an optional cargo door 1.24m x 1.32m can be fitted to ease loading and unloading of bulky cargo.

I accompanied Luke Scott, senior Beechcraft demonstration pilot, as he performed the pre-flight walk around inspection. Big was the word that sprung to mind when I first encountered the 350i, and the ER’s aft nacelle fuel tanks made it appear bigger still.

Like the 350i, with MTOW 6,800kg (15,000lbs), the 350ER is granted a Commuter Category exemption from the FAA, as its MTOW of 7,480kg exceeds the statutory 5,670kg maximum. When compared to an empty 350i (with like cabin interior), the 350ER weighs 126kg more. Beefed up landing gear and nacelle fuel tanks account for most of the difference. The beefed up landing gear is evidenced by main gear wheels sticking out 4in/10cm and only enclosed by half doors, as opposed to the 350i’s fully enclosed flush main wheels.

Entry into the spacious cabin was via the standard passenger entry door, which incorporated four steps. The cabin cross section is nearly rectangular, 1.45m high and 1.37m wide. With a total length of 5.94m, 10m³ of usable volume is provided.

The exposed seat rails allow for a good amount of configuration flexibility. In a high-capacity seating configuration 11 lightweight forward facing chairs along with a fold-up seat and belted lavatory give seating for 13.

There is enough space for eight heavier VIP seats to be arranged in a dual club layout. Based on customer need a number of VIP and lightweight seat combinations are possible.

The ER’s flightdeck is nearly identical to the 350i’s, featuring a Collins Pro Line 21 avionics suite. Three 20.3cm x 25.4cm displays, two PFDs and one MFD, cover nearly half of the forward instrument panel.

Arranged to enhance single pilot operations, systems control panels are located along the bottom edge of the panel. Notably, the ER’s fuel control panel is revised to control the added nacelle fuel tanks.

TCAS and TAWS are also standard, as well as an out of the box RVSM capability. As capable as it is, there is still ample room for improvement. While equipped with a digital Engine Indicating System (EIS), CAUTIONs are displayed on a glareshield mounted light panel. Incorporation of a full EICAS system would bring the ER’s flight deck up to a late 20th century level.

Scott guided completion of the pre-start checks, using the yoke mounted buttons to sequence through the checklist. While quite capable of starting on battery power alone, an external power cart was used to start both the ER’s Pratt & Whitney Canada PT6A-60A engines. Two critical items checked post start were the propeller autofeather and rudder boost systems. Proper function of these two systems greatly eases pilot workload in the event of an engine failure.

Gerzanics was very impressed with the type's flexibility and responsiveness

John Beckman

Flaps Up Takeoff

The ER’s manual nose wheel steering has a mechanical limit of 14° left and 12° right. For taxi in tight quarters up to 48° of nosewheel deflection is available with the use of differential braking and asymmetric thrust.

While it was a short taxi for an intersection departure off RWY30L, I found the NWS allowed me to accurately track centerlines. With 1,090kg of fuel and three occupants, TOGW was only 5,900kg, well below the 7,480kg maximum.

At this light weight, Scott recommended we do a flaps UP takeoff. Beechcraft recommends a flaps UP TO when engine out climb performance, not runway length, is the limiting factor. With the propellers set to MAX, I set 1700rpm with the throttles as we rolled down the runway. Moderate right rudder pedal pressure, needed to counteract the p-factor induced yawing motion, reminded me that I wasn’t in a jet. That being said it leapt off the runway in short order after a ground roll of approximately 600m. I immediately retracted the gear and attained an initial climb attitude of 17°. At a Vx of 135KIAS (best angle of climb) the climb rate stabilised at about 4,000ft/min (20m/s). FD guidance was used to follow the departure ground track as we headed towards Hollister, California (KCVH). In the climb I set the propeller RPM to 1600, and advanced the throttles to maintain a torque of 100%.

Initial climb speed was 175KIAS, with the target speed decreasing 10KIAS every 5,000ft above 10,000ft. During the climb engine ITT increased and once it reached 785°C, ITT rather than torque became the climb power control parameter. Several ATC hold downs delayed our climb, the ER leveling off at FL250 in less than 14 minutes after brake release. Beechcraft published time to climb for test day conditions is only 12 minutes, a credible figure based on observed performance.

Once level at FL250 I set a cruise rpm of 1,500 and a total fuel flow of 700PPH, to approximate a maximum cruise power point. At 196KIAS the ER stopped accelerating to a true airspeed of 293kt (ISA +12°C), agreeing nicely with Beechcraft book data.

At MTOW and full fuel Beechcraft lists a NBAA IFR range of 2,350nm (4,340km) at Long Range Cruise (LRC) speed (259KTAS). At high speed cruise (HSC) settings for same conditions the speed increases to 266KTAS and range decreases slightly to 2,240nm.

The ER’s range is significantly greater than its corporate configured stablemate, the 350i, due to its additional 718kg of fuel.

Loitering Permitted

The extra fuel carried by the ER can also be put to good use just hanging around. Persistence is often listed as a desirable attribute for an ISR asset. Also the ER has a good payload capability. With a single pilot and full fuel tanks an ER has a mission package capability of 856kg.

According to Beechcraft data the ER at FL260 has an endurance of 12hrs and 12min (+ 45min reserve) with power set for maximum endurance. I slowed the ER to 120KIAS (target loiter speed) at FL250.

Total fuel flow was only 380pph/173kgh at ISA +12°C conditions, lending credence to Beechcraft’s book data. Human endurance should not be a limitation. The ER’s 6.5PSI (differential pressure) pressurization system can provide a SL cabin to 15,300ft. The cabin is relatively spacious and a standard lavatory provides at least minimal creature comforts.

With a ceiling of 35,000ft and over 12h of endurance, the ER doesn’t neatly fit into any of the US Air Force UAS classifications.

What it does offer is an extremely flexible platform with a heavy (by UAS standards) payload capability. For some operators a manned ER may be a better choice for the ISR role than a UAS.

Search and Rescue

While still at altitude I re-familiarised myself with the Rockwell Collins flight management system. As with my prior King Air flight I found its operation fairly intuitive.

One feature unique to the ER’s FMS is the “search” page. It had four prompts for search options: LADDER, EXP SQUARE, SECTOR and CIRCLE. As a Civil Air Patrol Cadet in my youth and as an Airborne Forward Air Controller in the USAF I had occasion to conduct practice aerial searches.

While enroute to ROBIE, a high altitude waypoint south of KSJC, as an FMS exercise I loaded a “LADDER” search pattern.

On a fully missionised ER the sensor operator could enter a recommended search pattern to be flown with pilot approval. While ATC conditions did not allow our actual flight of the search pattern, the AP would have tracked the designated ground track.

Field of view from the cockpit seats is fairly good, and with the AP engaged both cockpit crew would be free to scan the designated search area. Once the target was located, a CIRCLE pattern could be selected to fly a constant radius path around it.

Hollister Circuits

After completion of the mission relevant events, I started a descent and turned the ER towards Hollister Municipal Airport (KCVH). Scott monitored me I as I loaded the RNAV (GPS) RWY 31 approach procedure. I engaged the AP and once coupled up, I needed only control airspeed with the manual throttles. Hollister is an uncontrolled field, and with the AP engaged I was able to keep my eyes out of the cockpit to scan for other traffic.

Having our own ship position displayed on the MFD’s chart depiction enhanced my ­situational awareness.

Flaps were set to the DN (fully extended) position, for a short field landing. At 50ft AGL I retarded the throttles to IDLE and with minimal flare planted the ER on the 6,350ft/1,940m long runway. Moderate wheel braking and application of reverse thrust from the 2.67m (104in)-diameter four-bladed Hartzell propellers brought the aircraft to a stop after less than a 500m ground roll.

After taxi back and takeoff from RWY31 I was able to do several more visual circuits at Hollister before our return to San Jose. One was a simulated failure of the left engine at pattern altitude.

At 120KIAS, with gear extended, available rudder trim nulled out right rudder pressure needed for coordinated flight. Had the failure occurred during climb out, I am sure I would have appreciated the ER’s rudder boost system. Flaps were kept at APPROACH, until landing was assured when flaps were set to DN. On final I centred the rudder trim, with only light right rudder pressure needed at the low approach power setting.

Flaps were set to APPROACH for our last take off at Hollister. Once airborne ATC cleared us directly KLIDE, a point outside the FAF, for an ILS to RWY30L at KSJC.

The hand flown approach to a full stop landing was a fitting end to what had been a enjoyable and illuminating flight.

The type boats a ceiling of 35,000ft and over 12hr of endurance

John Beckman

Jack Beats a King

The ER’s cabin provides plenty of usable volume for the installation of any number of customer specific configurations.

Its high TOGW, 680kg greater than the 350i’s, allows for the installation of up to 856kg of mission specific payload (kit plus operators). The extra fuel provided by the engine nacelle mounted tanks give it exceptional range and endurance capabilities.

At FL260 the ER has a 304KTAS high speed cruise capability, allowing deployment at speeds far in excess of typical propeller driven UAS assets.

For some operators the manned ER may be a wise choice for ISR ­missions.

With over 120 delivered to date, the King Air 350ER has shown itself to be a jack of all trades.